Gastrointestinal cancer represents one of the major reasons for tumor related death in the United States. Current treatment options are limited to surgery, chemotherapy, radiation therapy and molecular targeted therapy and new treatment options are urgently needed. We have been enrolling patients on the following protocols: NCI-19-C-0033:Phase II Study of Nivolumab (anti-PD1), Tadalafil and Oral Vancomycin in Patients with Refractory Primary Hepatocellular Carcinoma or Liver Dominant Metastatic Cancer from Colorectal or Pancreatic Cancers; NCI-17-C-0092: A Phase I/II Study of Pexa-Vec Oncolytic Virus in Combination with Immune Checkpoint Inhibition in Refractory Colorectal Cancer; NCI-17-C-0082: A Phase 2 Study of Pembrolizumab, a Monoclonal Antibody Against PD-1, in Combination with Capecitabine and Oxaliplatin (CAPOX) in Subjects with Advanced Biliary Tract Carcinoma (BTC); NCI-16-C-0135: A Pilot Study of Combined Immune Checkpoint Inhibition in combination with ablative therapies in Subjects with Hepatocellular Carcinoma (HCC) or Biliary Tract Carcinomas (BTC) ; NCI-15-C-0027: A Pilot Study of Immune Checkpoint inhibition (Durvalumab with or without Tremelimumab) in Combination with Radiation Therapy in Patients with Unresectable Pancreatic Cancer